Burning fructose comes at a cost. In the short-term, it produces lactic acid. In the long-term, other studies have suggested that burning fructose increases the risk of heart disease, diabetes, and cancer. “They obviously need other adaptations to make this work,” says Park.
For example, the mole-rats almost certainly get their fructose from their diet, but where do they store the sugar? When we humans eat a high-fructose diet, we convert the stuff into fat—which is why fructose has been linked to obesity and metabolic problems. “The next step is to identify how the mole-rats store fructose so they can use it directly without encountering the known issues of cancer and metabolic syndrome,” says Rochelle Buffenstein from Calico, who has worked with these animals before.
Park thinks this discovery might eventually be useful in protecting human health. Strokes, heart attacks, and other kinds of trauma are so lethal because they deprive the body—and the brain, in particular—of oxygen. Perhaps the naked mole-rat’s ability to shrug off a debilitating lack of oxygen might inspire new strategies for surviving these conditions. After all, we humans carry the same fructose-importing pumps and the same fructose-burning enzymes—we just don’t use them in the same way.
But for that reason, “translating the findings of this paper to a medical context might be challenging,” says Krishnan. That’s because naked mole-rats have a lot of proteins that import fructose into their tissues—a trait that humans do not share. Under normal conditions, it would be hard for us to send enough fructose to reach the brain or heart.
Along similar lines, other scientists are looking to the mole-rats’ bizarre biology for clues to killing pain and preventing cancer. Which raises the question: why exactly do these particular animals have such a cluster of weird traits? Why them, and not any other burrowing mammal like moles, badgers, or even other mole-rats?
“With the caveat that nobody really knows, my feeling is that it all relates to their ecology,” says Park. Millions of years ago, their ancestors migrated into the Horn of Africa—an arid region with very sparse resources. In these deserts, the naked mole-rats almost entirely feed on tubers—root vegetables about the size of a basketball. “If you find one, it’s payday for a long time, but they’re so dispersed that you need a large number of animals working together to find one,” says Park.
If they worked alone, as most burrowing mammals do, they simply wouldn’t find enough food. But a colony of 300 mole-rats can dig in a multitude of different directions, and collectively track down the scarce but bountiful tubers. That’s probably the origin of their ant-like social structures. And it explains a lot more. A large colony of underground animals would quickly use up all the available oxygen, so they needed to evolve ways of dealing with that. They started burning fructose, which produced lactic acid—maybe that’s why the mole-rats evolved an immunity to acid and pain. They also slowed down their metabolism, which might explain their very long life. And if you’re long-lived, you’ll need ways of avoiding cancer.
“It’s like we’re working with an animal from another planet,” says Park. “They’re so unusual because they’ve been evolving in this weird alien atmosphere for millions of years.”